The idea that suffering is a good thing because it helps you enjoy the nice parts in life is absolute crap. Which shouldn't be deep, but I've heard that crap hundreds of times and yet I don't think I've ever heard anybody actually contest it directly.
Why do so many people wish they were kids again? Because they didn't have to deal with so many of the miseries that they have to deal with as adults. They were able to have and enjoy lots of fun without having all the looming worries that often come with adult life.
If the lows made the highs more enjoyable, then life would feel extra good after you experienced terrible miseries. There doesn't ever seem to be a rock bottom where things can't get worse, so experiencing your normal life after going through suffering worse than you realized was possible should be blissful, because it would metaphorically be like going from sea level to the Challenger Deep and then coming out of those soul crushing depths to realize that your old normal is now comparibly higher than Mount Everest.
Instead, going through hell just makes life unbearable and exhausting.and going back to normal after you've been through hell over and over just makes you anticipate the next trip to hell.